Many technical systems require a certain time after a new set point (reference variable) has been specified in order to reach this new set point or reference state. For example a heating system requires, after a room temperature has been specified that is higher than a currently measured temperature, a while until this higher room temperature is reached in the room. The system thus reaches the specified set point only after a delay. Accordingly, systems which reach their set point or reference state only after a certain time span are referred to in the present disclosure as being “affected by delays”. The delay is substantially determined by the performance capability, with which the system reacts to a sudden change in the reference variable to reach the new set point within a certain time. Therefore, where reference is made within the scope of this disclosure to “performance capability”, this means the speed, at which a new set point is reached in the event of a sudden change in the reference variable.
Nowadays consumers expect technical systems to be immediately available with the desired performance level or power when needed. If systems cannot achieve this on account of physical conditions, consumers frequently decide to permanently operate systems at the desired performance level or power, even if the continuous operation of the system is associated with higher energy consumption. A typical example is constituted by heating systems. A consumer who has been away and is coming home would like to return to a warm home. In order to guarantee this, he frequently decides to operate the heating system with non-reduced power also during his absence. The savings advantage achieved by “turning down” the heating system often has a lower significance in the consumer's perception than the comfort of a warm home upon arrival. In contrast, the savings advantage with systems that are immediately available with the desired power is the predominant factor for the average consumer. A typical example of this is electric light from a light bulb. When the light switch is activated, light is immediately available with virtually maximum power. Switching off the light does not therefore mean any loss of comfort, or only a limited loss of comfort, for the consumer.
On account of physical conditions, the reaction behaviour (reaching of the specified reference state or set point by the system) of systems affected by delays to a sudden change in the reference variable in general cannot be accelerated, or can only be accelerated to a limited extent. Consequently, in the past, different technical solutions were concocted that were intended to automatically achieve an adaptation of the power requirement to the needs of a user.
A classic example from the state of the art is timers, which automatically reach and maintain a specified power on a system affected by delays as a function of the time of day. A disadvantage of such systems is that timers can only insufficiently reflect the actual power needs of a user of the system affected by delays. Although a timer can reproduce the usual daily routine of a user well, it is by no means able to react dynamically to changes in the needs of the user. For example, a timer of a heating system will always switch on the heating at the programmed switch-on time, irrespective of whether the user actually requires this at this point in time. Timers are commonly set so that the heating switches on for example daily at 1700 hours, this setting being based upon the assumption that the user comes home at 1700 hours. If he does not actually come home at this time, the heating is still switched on and heat energy is thus wasted. Similarly, a timer cannot detect if a user returns at an earlier time than the programmed time.
A modern approach to the needs-based control of building technical components, such as for example a HVAC (Heating, Ventilation and Air Conditioning) system, is described in DE 10 2011 052 467. According to the solution proposed therein, a building technical component is to be operated at a higher power if a user of the building is within a geozone defined around the building. A more extensive geozone concept of this application provides for the defining of a plurality of different geozones around a building, whereby geozones lying closer to the building are respectively linked with a higher power specification to the building technical component. The power can thus be increased in stages as the user approaches the building.
In the case of such a geozone-based control of the power specification, the specifying of the power is determined substantially as a function of the distance of a user from the building. A disadvantage of such distance-based controls is that the distance only indirectly correlates with an actual arrival time of the user, since the distance alone does not contain any information on the actual journey duration of the user from the geozone/the geoposition to the building. Decisive influencing factors on the journey duration are indeed, besides the distance, also the current speed, the selected travel route, the mode of travel (car, bicycle, walking) and/or the currently prevailing traffic conditions. The arrival time can thus only be imprecisely predetermined from the distance alone. This leads to a power specification to the system that is not optimally tailored to the arrival of the building user.
A further disadvantage of the known geozone-based control is that a system is constantly only lowered to a power specification that is determined on the basis of the current distance of the user from the building. If a user remains for a longer time at a certain location, it would be advantageous if the system could also be operated for the majority of this time with a lower power specification than would be the case purely according to the distance. However, such a further reduction in the power specification is not possible with a purely distance-based control, because a corresponding power requirement is always assigned to a distance with this type of control system.